Prosthetic heart valve having identifiers for aiding in radiographic positioning

ABSTRACT

A prosthetic heart valve having identifiers for aiding in radiographic positioning is described.

This application claims the benefit under 35 U.S.C. §119(c) of U.S. patent application Ser. No. 61/192,201, filed Sep. 15, 2008, which is herein incorporated by reference in its entirety. The present invention relates generally to prosthetic heart valves, and specifically to techniques for accurately positioning such valves during implantation procedures.

FIELD OF THE INVENTION Background of the Invention

Aortic valve replacement in patients with severe valve disease is a common surgical procedure. The replacement is conventionally performed by open heart surgery, in which the heart is usually arrested and the patient is placed on a heart bypass machine. In recent years, prosthetic heart valves have been developed which are implanted using minimally invasive procedures such as transapical or percutaneous approaches. These methods involve compressing the prosthesis radially to reduce its diameter, inserting the prosthesis into a delivery tool, such as a catheter, and advancing the delivery tool to the correct anatomical position in the heart. Once properly positioned, the prosthesis is deployed by radial expansion within the native valve annulus.

While these techniques are substantially less invasive than open heart surgery, the lack of line-of-sight visualization of the prosthesis and the native valve presents challenges, because the physician cannot see the actual orientation of the prosthesis during the implantation procedure. Correct positioning of the prostheses is achieved using radiographic imaging, which yields a two-dimensional image of the viewed area. The physician must interpret the image correctly in order to properly place the prostheses in the desired position. Failure to properly position the prostheses sometimes leads to device migration or to improper functioning. Proper device placement using radiographic imaging is thus critical to the success of the implantation.

PCT Publication WO 05/002466 to Schwammenthal et al., which is assigned to the assignee of the present application and is incorporated herein by reference, describes prosthetic devices for treating aortic stenosis.

PCT Publication WO 06/070372 to Schwammenthal et al., which is assigned to the assignee of the present application and is incorporated herein by reference, describes a prosthetic device having a single flow field therethrough, adapted for implantation in a subject, and shaped so as to define a fluid inlet and a diverging section, distal to the fluid inlet.

US Patent Application Publication 2006/0149360 to Schwammenthal et al., which is assigned to the assignee of the present application and is incorporated herein by reference, describes a prosthetic device including a valve-orifice attachment member attachable to a valve in a blood vessel and including a fluid inlet, and a diverging member that extends from the fluid inlet, the diverging member including a proximal end near the fluid inlet and a distal end distanced from the proximal end. A distal portion of the diverging member has a larger cross-sectional area for fluid flow therethrough than a proximal portion thereof.

US Patent Application Publication 2005/0197695 to Stacchino et al., describes a cardiac-valve prosthesis adapted for percutaneous implantation. The prosthesis includes an armature adapted for deployment in a radially expanded implantation position, the armature including a support portion and an anchor portion, which are substantially axially coextensive with respect to one another. A set of leaflets is coupled to the support portion. The leaflets can be deployed with the armature in the implantation position. The leaflets define, in the implantation position, a flow duct that is selectably obstructable. The anchor portion can be deployed to enable anchorage of the cardiac-valve prosthesis at an implantation site.

The following patents and patent application publications, are set forth as background:

-   U.S. Pat. No. 6,312,465 to Griffin et al. -   U.S. Pat. No. 5,908,451 to Yeo -   U.S. Pat. No. 5,344,442 to Deac -   U.S. Pat. No. 5,354,330 to Hanson -   US Patent Application Publication 2004/0260389 to Case et al. -   U.S. Pat. No. 6,730,118 to Spencer et al. -   U.S. Pat. No. 7,018,406 to Seguin et al. -   U.S. Pat. No. 7,018,408 to Bailey et al. -   U.S. Pat. No. 6,458,153 and US Patent Application Publication     2003/0023300 to Bailey et al. -   US Patent Application Publication 2004/0186563 to Lobbi -   US Patent Application Publication 2003/0130729 to Paniagua et al. -   US Patent Application Publication 2004/0236411 to Sarac et al. -   US Patent Application Publication 2005/0075720 to Nguyen et al. -   US Patent Application Publication 2006/0058872 to Salahieh et al. -   US Patent Application Publication 2005/0137688 to Salahieh et al. -   US Patent Application Publication 2005/0137690 to Salahieh et al. -   US Patent Application Publication 2005/0137691 to Salahieh et al. -   US Patent Application Publication 2005/0143809 to Salahieh et al. -   US Patent Application Publication 2005/0182483 to Osborne et al. -   US Patent Application Publication 2005/0137695 to Salahieh et al. -   US Patent Application Publication 2005/0240200 to Bergheim -   US Patent Application Publication 2006/0025857 to Bergheim et al. -   US Patent Application Publication 2006/0025855 to Lashinski et al. -   US Patent Application Publication 2006/0047338 to Jenson et al. -   US Patent Application Publication 2006/0052867 to Revuelta et al. -   US Patent Application Publication 2006/0074485 to Realyvasquez -   US Patent Application Publication 2006/0259136 to Nguyen et al. -   U.S. Pat. No. 7,137,184 to Schreck -   U.S. Pat. No. 6,296,662 to Caffey

SUMMARY OF THE INVENTION

In some embodiments of the present invention, a prosthetic heart valve prosthesis comprises three commissural posts to which are coupled a prosthetic valve. The commissural posts are shaped so as define therethrough respective openings that serve as radiographic identifiers during an implantation procedure. During the procedure, the valve prosthesis, including the commissural posts, is initially collapsed within a delivery tube. Before expanding the valve prosthesis, a physician uses radiographic imaging, such as x-ray fluoroscopy, to provide visual feedback that aids the physician in rotationally aligning the commissural posts with respective native commissures of a native semilunar valve. The identifiers strongly contrast with the rest of the commissural posts and the valve prosthesis, which comprise a radiopaque material. Without such identifiers, it is generally difficult to three-dimensionally visually distinguish the commissural posts from one another and from the rest of the valve prosthesis, because the radiographic imaging produces a two-dimensional representation of the three-dimensional valve prosthesis. When the valve prosthesis is in a collapsed state, the elements thereof overlap in a two-dimensional image and are generally indistinguishable.

In some embodiments of the present invention, the physician selects one of the commissural posts having a radiographic identifier, and attempts to rotationally align the selected post with one of the native commissures, such as the commissure between the left and right coronary sinuses. Because the radiographic image is two-dimensional, all of the posts appear in the image as though they are in the same plane. The physician thus cannot distinguish between two possible rotational positions of the posts: (1) the desired rotational position, in which the selected post faces the desired native commissure, and (2) a rotational position 180 degrees from the desired rotational position, in which the selected post faces the side of the native valve opposite the desired native commissure. For example, if the desired native commissure is the commissure between the left and right coronary sinuses, in position (2) the post is rotationally aligned with the noncoronary sinus, although this undesired rotation is not apparent in the radiographic image.

To ascertain whether the posts are in rotational position (1) or (2), the physician slightly rotates the valve prosthesis. If the radiographic identifier on the selected post appears to move in the radiographic image in the same direction as the rotation, the selected post is correctly rotationally aligned in the desired position (1). If, on the other hand, the radiographic identifier appears to move in the direction opposite the direction of rotation, the selected post is incorrectly rotationally aligned in position (2). To correct the alignment, the physician may rotate the valve prosthesis approximately 60 degrees in either direction, thereby ensuring that one of the two other posts is now rotationally aligned in position (1). (The valve prosthesis typically has three-fold rotational symmetry, such that rotation of 60 degrees is sufficient to properly align one of the posts with the selected native commissure, and the prosthesis need not be rotated a full 180 degrees.) In these embodiments, the openings through the posts that define the radiographic identifiers may assume any convenient shape, such as a slit.

In some embodiments of the present invention, the openings that define the radiographic identifiers are shaped to be reflection-asymmetric along respective post axes that are generally parallel with a central longitudinal axis of the prosthesis when the posts assume their collapsed position. For example, the identifiers may be shaped as one or more reflection-asymmetric characters, such as numbers or letters of the alphabet, e.g., B, C, D, E, etc. The physician can thus readily identify the true orientation of the selected post that appears to be rotationally aligned with the selected native commissure. If the identifier on the selected post appears in the correct left-right orientation, the selected post is aligned in the desired position (1). If, on the other hand, the identifier appears as the mirror image of its correct left-right orientation, the selected post is incorrectly rotationally aligned in position (2). To correct the alignment, the physician may rotate the valve prosthesis approximately 60 degrees in either direction, thereby ensuring that one of the two other posts is now rotationally aligned in position (1).

There is therefore provided, in accordance with an embodiment of the present invention, apparatus including a valve prosthesis, which includes a prosthetic heart valve, and three or more commissural posts, to which the prosthetic heart valve is coupled. The posts are arranged circumferentially around a central longitudinal axis of the valve prosthesis, and are configured to assume a collapsed position prior to implantation of the prosthesis, and an expanded position upon the implantation of the prosthesis. One or more of the commissural posts are provided with respective radiographic identifiers that are shaped to be reflection-asymmetric about respective post axes that are generally parallel with the central longitudinal axis when the posts assume the collapsed position.

For some applications, the radiographic identifiers have the shape of one or more reflection-asymmetric characters.

In an embodiment, the one or more of the commissural posts are shaped to define respective openings therethrough which define the respective radiographic identifiers. Alternatively, the radiographic identifiers include a material having a first radiopacity that is different from a second radiopacity of the commissural posts, which material is coupled to the one or more of the commissural posts.

For some applications, the valve prosthesis includes exactly three commissural posts.

There is further provided, in accordance with an embodiment of the present invention, a method including:

providing a valve prosthesis that includes a prosthetic heart valve, and three or more commissural posts, to which the prosthetic heart valve is coupled, which posts are arranged circumferentially around a central longitudinal axis of the valve prosthesis, and are configured to assume a collapsed position prior to implantation of the prosthesis, and an expanded position upon the implantation of the prosthesis, and at least one of which commissural posts is provided with a radiographic identifier;

while the posts assume the collapsed position, placing, via a blood vessel of the subject, the valve prosthesis at least partially in a heart of a subject in a vicinity of a native heart valve having native commissures;

generating a fluoroscopic image of the native commissures and valve prosthesis; and

rotationally aligning the at least one of the commissural posts with one of the native commissures using the radiographic identifier visible in the image.

In an embodiment, rotationally aligning includes rotating the valve prosthesis; observing whether the at least one of the commissural posts appears to move in the image in the same direction that the valve prosthesis is rotated, or in an opposite direction; and, if the at least one of the commissural posts appears to move in the image in the opposite direction, rotating the valve prosthesis to correct a rotational alignment, of the valve prosthesis.

For some applications, the valve prosthesis includes exactly three commissural posts, and is configured to have three-fold rotational symmetry, and rotating the valve prosthesis to correct the rotational alignment includes rotating the valve prosthesis approximately 60 degrees.

In an embodiment, the radiographic identifier is shaped to be reflection-asymmetric about a post axis of the at least one of the commissural posts, which axis is generally parallel with the central longitudinal axis when the posts assume the collapsed position. For some applications, the radiographic identifier has the shape of a reflection-asymmetric character.

For some applications, rotationally aligning includes observing in the image whether the radiographic identifier appears in a correct left-right orientation, and, if the radiographic identifier does not appear in the correct left-right orientation, rotating the valve prosthesis to correct a rotational alignment of the valve prosthesis. For some applications, the valve prosthesis includes exactly three commissural posts, and is configured to have three-fold rotational symmetry, and rotating the valve prosthesis to correct the rotational alignment includes rotating the valve prosthesis approximately 60 degrees.

In an embodiment, the at least one of the commissural posts is shaped to define an opening therethrough which defines the radiographic identifier. Alternatively, the radiographic identifier includes a material having a first radiopacity that is different from a second radiopacity of the at least one of the commissural posts, which material is coupled to the at least one of the commissural posts.

For some applications, the one of the native commissures is a native commissure (C_(RL)) between a left coronary sinus and a right coronary sinus, and rotationally aligning includes rotationally aligned the one of the commissural posts with the C_(RL).

There is still further provided, in accordance with an embodiment of the present invention, a method including:

providing a valve prosthesis that includes a prosthetic heart valve, and three or more commissural posts, to which the prosthetic heart valve is coupled, which posts are arranged circumferentially around a central longitudinal axis of the valve prosthesis, and are configured to assume a collapsed position prior to implantation of the prosthesis, and an expanded position upon the implantation of the prosthesis;

while the posts assume the collapsed position, placing, via a blood vessel of the subject, the valve prosthesis at least partially in a heart of a subject in a vicinity of a native heart valve having native commissures;

generating a fluoroscopic image of the native commissures and valve prosthesis; and

rotationally aligning the at least one of the commissural posts with one of the native commissures by:

rotating the valve prosthesis,

observing whether the at least one of the commissural posts appears to move in the image in the same direction that the valve prosthesis is rotated, or in an opposite direction, and

if the at least one of the commissural posts appears to move in the image in the opposite direction, rotating the valve prosthesis to correct a rotational alignment of the valve prosthesis.

For some applications, the valve prosthesis includes exactly three commissural posts, and is configured to have three-fold rotational symmetry, and rotating the valve prosthesis to correct the rotational alignment includes rotating the valve prosthesis approximately 60 degrees.

There is additionally provided, in accordance with an embodiment of the present invention, apparatus including a valve prosthesis, which includes:

a prosthetic heart valve;

a support structure, which includes a first material having a first radiopacity; and

one or more radiographic identifiers, which include a second material having a second radiopacity different from the first radiopacity, and which are coupled to the support structure at respective locations.

In an embodiment, the radiographic identifiers are shaped to be reflection-asymmetric about respective identifier axes that are generally parallel with a central longitudinal axis of the valve prosthesis.

For some applications, the identifiers are arranged circumferentially around a central longitudinal axis of the valve prosthesis.

For some applications, the support structure is shaped so as to define a bulging proximal skirt, and the identifiers are coupled to the skirt.

For some applications, the support structure includes three or more commissural posts, to which the prosthetic heart valve is coupled, which posts are arranged circumferentially around a central longitudinal axis of the valve prosthesis, the locations at which the identifiers are coupled to the support structure are not on the posts, and the locations are radially aligned with the posts.

For some applications, the support structure includes three or more commissural posts, to which the prosthetic heart valve is coupled, which posts are arranged circumferentially around a central longitudinal axis of the valve prosthesis, and the locations at which the identifiers are coupled to the support structure are on the posts.

The present invention will be more fully understood from the following detailed description of embodiments thereof, taken together with the drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a fully-assembled valve prosthesis, in accordance with an embodiment of the present invention;

FIGS. 2A and 2B are schematic illustrations of a collapsible outer support structure and a collapsible inner support structure, respectively, prior to assembly together into the valve prosthesis of FIG. 1, in accordance with an embodiment of the present invention;

FIG. 3 is a schematic illustration of a subject undergoing a transapical or percutaneous valve replacement procedure, in accordance with an embodiment of the present invention;

FIG. 4 shows an exemplary fluoroscopic view generated with a fluoroscopic system during a valve replacement procedure, in accordance with an embodiment of the present invention;

FIG. 5 shows an exemplary ultrasound view generated with an ultrasound probe during a valve replacement procedure, in accordance with an embodiment of the present invention;

FIGS. 6A and 6B are schematic and fluoroscopic views, respectively, of the valve prosthesis of FIG. 1 in a collapsed position in a catheter, in accordance with an embodiment of the present invention;

FIGS. 7A and 7B are schematic illustrations of the valve prosthesis of FIG. 1 in situ upon completion of transapical and retrograde transaortic implantation procedures, respectively, in accordance with respective embodiments of the present invention;

FIGS. 7C-7E are schematic illustrations of an implantation procedure of an alternative configuration of the valve prosthesis of FIG. 1, in accordance with an embodiment of the present invention;

FIGS. 8A-B are schematic illustrations of the valve prosthesis of FIG. 1 positioned within the aortic root, in accordance with an embodiment of the present invention;

FIG. 9 is a flow chart that schematically illustrates a method for ascertaining whether the valve prosthesis of FIG. 1 or FIGS. 7C-E are properly rotationally aligned with the native commissures, in accordance with an embodiment of the present invention and

FIGS. 10A and 10B are schematic illustrations of reflection-asymmetric radiographic identifiers on commissural posts of the valve prosthesis of FIG. 1 or FIGS. 7C-E, in accordance with respective embodiments of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 is a schematic illustration of a fully-assembled valve prosthesis 10, in accordance with an embodiment of the present invention. Typically, valve prosthesis 10 comprises exactly three commissural posts 11, arranged circumferentially around a central longitudinal axis 13 of valve prosthesis 10. Valve prosthesis 10 further comprises a prosthetic distal valve 104 coupled to coupled to commissural posts 11. Valve 104 typically comprises a pliant material 105. Pliant material 105 of valve 104 is configured to collapse inwardly (i.e., towards central longitudinal axis 13) during diastole, in order to inhibit retrograde blood flow, and to open outwardly during systole, to allow blood flow through the prosthesis. For some applications, valve prosthesis 10 comprises a collapsible inner support structure 12 that serves as a proximal fixation member, and a collapsible outer support structure 14 that serves as a distal fixation member.

One or more (e.g., all) of commissural posts 11 are shaped so as define therethrough respective openings 16 that serve as radiographic identifiers during an implantation procedure, as described hereinbelow with reference to FIGS. 3-8B. The openings may assume any convenient, shape, for example, slits, as shown in FIGS. 1, 2A-B, and 6A-B. In some embodiments, the openings are shaped to be reflection-asymmetric along respective post axes generally parallel with central longitudinal axis 13 of prosthesis 10 when the posts assume their collapsed position, as described hereinbelow with reference to FIGS. 10A-B. For some applications, in addition to serving as the radiographic identifiers, openings 16 are used for coupling valve 104 to support structures 12 and 14. Although pliant material 105 of valve 104 at least partially fills openings 16, the material is substantially more radiolucent than commissural posts 11, and thus does not reduce the radiographic visibility of the radiographic identifiers. Alternatively, one or more of posts 11 do not necessarily define openings 16, and the one or more posts instead comprise radiographic identifiers comprising a material having a radiopacity different from (greater or less than) the radiopacity of posts 11, such as gold or tantalum.

Valve prosthesis 10 is configured to be placed in a native diseased valve of a subject, such as a native stenotic aortic or pulmonary valve, using a minimally-invasive approach, such as a beating heart transapical procedure, such as described hereinbelow with reference to FIG. 7A, or a retrograde transaortic procedure, such as described hereinbelow with reference to FIG. 7B. As used in the present application, including in the claims, a “native semilunar valve” is to be understood as including: (a) native semilunar valves that include their native leaflets, and (b) native semilunar valves, the native leaflets of which have been surgically excised or are otherwise absent.

Reference is made to FIG. 2A, which is a schematic illustration of collapsible outer support structure 14 prior to assembly with inner support structure 12, in accordance with an embodiment of the present invention. In this embodiment, outer support structure 14 is shaped so as to define a plurality of distal diverging strut supports 20, from which a plurality of proximal engagement arms 22 extend radially outward in a proximal direction. Engagement arms 22 are typically configured to be at least partially disposed within aortic sinuses of the subject, and, for some applications, to engage and/or rest against floors of the aortic sinuses, and to apply an axial force directed toward a left ventricle of the subject. Outer support structure 14 comprises a suitable material that allows mechanical deformations associated with crimping and expansion of valve prosthesis 10, such as, but not limited to, nitinol or a stainless steel alloy (e.g., AISI 316).

Reference is made to FIG. 23, which is a schematic illustration of collapsible inner support structure 12 prior to assembly with outer support structure 14, in accordance with an embodiment of the present invention. For some applications, inner support structure 12 is shaped so as to define a plurality of distal diverging inner struts 30, and a bulging proximal skirt 32 that extends from the struts. A proximal portion 34 of proximal skirt 32 is configured to engage a left ventricular outflow tract (LVOT) of the subject and/or periannular tissue at the top of the left ventricle. A relatively narrow throat section 36 of proximal skirt 32 is configured to be positioned at a valvular annulus of the subject, and to engage the native valve leaflets. Inner support structure 12 comprises, for example, nitinol, a stainless steel alloy, another metal, or another biocompatible material.

Reference is again made to FIG. 1. Inner and outer support structures 12 and 14 are assembled together by placing outer support structure 14 over inner support structure 12, such that cuter strut supports 20 are aligned with, and typically support, respective inner struts 30, and engagement arms 22 are placed over a portion of proximal skirt 32. Inner struts 30 and outer strut supports 20 together define commissural posts 11.

Although exactly three commissural posts 11 are shown in the figures, for some applications valve prosthesis 10 comprises fewer or more posts 11, such as two posts 11, or four or more posts 11.

Typically, valve prosthesis 10 further comprises a graft covering 106 which is coupled to proximal skirt 32, such as by sewing the covering within the skirt (configuration shown in FIG. 1) or around the skirt (configuration not shown). Inner support structure 12 thus defines a central structured body for flow passage that proximally terminates in a flared inlet (proximal skirt 32) that is configured to be seated within an LVOT immediately below an aortic annulus/aortic valve. For some applications, graft covering 106 is coupled at one or more sites to pliant material 105.

In an embodiment of the present invention, a portion of valve prosthesis 10 other than commissural posts 11, e.g., proximal skirt 32, is shaped so as to define openings 16 that serve as radiographic identifiers. Alternatively or additionally, the commissural posts or this other portion of the prosthesis comprise radiographic identifiers comprising a material having a radiopacity different from (greater or less than) the radiopacity of other portions of the prosthesis. For some applications, the radiographic identifiers are radially aligned with commissural posts 11.

FIG. 3 is a schematic illustration of a subject 200 undergoing a transapical or percutaneous valve replacement procedure, in accordance with an embodiment of the present invention. A fluoroscopy system 210 comprises a fluoroscopy source 213, a fluoroscopy detector 212, and a monitor 214. Fluoroscopy source 213 is positioned over subject 200 so as to obtain a left anterior oblique (LAO) projection of between 30 and 45, such as between 30 and 40, degrees with a 30-degree cranial tilt (for orthogonal projection of the annulus). Typically, imaging is enhanced using an ultrasound probe 216.

FIG. 4 shows an exemplary fluoroscopic view 220 generated with fluoroscopic system 210 during a valve replacement procedure, in accordance with an embodiment of the present invention. In the view, a right coronary sinus (RCS) 222 and a left coronary sinus (LCS) 224 are visible, as are the respective coronary arteries that originate from the sinuses. The view also shows a commissure 226 between the right and left sinuses (C_(RL)). RCS 222, LCS 224, and C_(RL) 226 serve as clear anatomical landmarks during the replacement procedure, enabling the physician to readily ascertain the layout of the aortic root.

FIG. 5 shows an exemplary ultrasound view 230 generated with ultrasound probe 216 during a valve replacement procedure, in accordance with an embodiment of the present invention. In the view, the RCS, LCS, and non-coronary sinus (N) are visible. The orientation of view 230 can be seen with respect to a sternum 232 and a spine 234, as well as with respect to fluoroscopy detector 212.

FIGS. 6A and 6B are schematic and fluoroscopic views, respectively, of valve prosthesis 10 in a collapsed position in a catheter 300, in accordance with an embodiment of the present invention. In this embodiment, openings 16 are shaped as slits. As can be seen in FIG. 6B, these slits are clearly visible with fluoroscopy.

Reference is made to FIGS. 7A and 7B, which are schematic illustrations of valve prosthesis 10 in situ upon completion of transapical and retrograde transaortic implantation procedures, respectively, in accordance with respective embodiments of the present invention.

In the transapical procedure, as shown in FIG. 7A, an introducer overtube or trocar 150 is inserted into a left ventricular apex 156 using a Seldinger technique. Through this trocar, a delivery catheter (not shown in the figure) onto which collapsed valve prosthesis 10 is mounted, is advanced into a left ventricle 357 where its motion is terminated, or through left ventricle 357 until the distal end of a dilator (not shown) passes native aortic valve leaflets 358. For example, apex 356 may be punctured using a standard Seldinger technique, and a guidewire may be advanced into an ascending aorta 360. Optionally, a native aortic valve 340 is partially dilated to about 15-20 mm (e.g., about 16 mm), typically using a standard valvuloplasty balloon catheter. (In contrast, full dilation would be achieved utilizing dilation of 20 mm or more.) Overtube or trocar 350 is advanced into the ascending aorta. Overtube or trocar 350 is pushed beyond aortic valve 340 such that the distal end of overtube or trocar 350 is located above the highest point of native aortic valve 340. The dilator is removed while overtube or trocar 350 remains in place with its distal end located above aortic valve 340. Alternatively, the procedure may be modified so that overtube or trocar 350 is placed within left ventricle 350 and remains within the left ventricle throughout the entire implantation procedure. Valve prosthesis 10 is advanced through the distal end of overtube or trocar 350 into ascending aorta 360 distal to native leaflets 358.

Valve prosthesis 10, typically while still within the catheter, is rotated to align arms 22 with aortic sinuses 364, as described hereinbelow with reference to FIGS. 8A-B or FIGS. 10A-B. After the prosthesis is properly rotationally aligned, withdrawal of the catheter causes engagement arms 22 to flare out laterally to an angle which is typically predetermined by design, and to open in an upstream direction. Gentle withdrawal of the delivery catheter, onto which prosthesis 10 with flared-out arms 22 is mounted, causes the arms to slide into aortic sinuses 364. Release of the device from the delivery catheter causes a lower inflow portion of prosthesis 10 to unfold and press against the upstream side of native leaflets 358, thereby engaging with the upstream fixation arms in the aortic sinuses. The upstream fixation arms serve as counterparts to the lower inflow portion of the prosthesis in a mechanism that locks the native leaflets and the surrounding periannular tissue for fixation.

For some applications, prosthesis 10 is implanted using techniques described with reference to FIGS. 5A-C in U.S. application Ser. No. 12/050,628, filed Mar. 18, 2008, entitled, “Valve suturing and implantation procedures,” which is incorporated herein by reference.

In the retrograde transaortic procedure, as shown in FIG. 7B, valve prosthesis 10 is positioned in a retrograde delivery catheter 450. A retrograde delivery catheter tube 451 of catheter 450 holds engagement arms 22, and a delivery catheter cap 452 holds proximal skirt 32 (not shown). A guidewire 490 is transaortically inserted into left ventricle 357. Optionally, stenotic aortic valve 340 is partially dilated to about 15-20 mm (e.g., about 16 mm), typically using a standard valvuloplasty balloon catheter. Retrograde delivery catheter 450 is advanced over guidewire 490 into ascending aorta 360 towards native aortic valve 340. Retrograde delivery catheter 450 is advanced over guidewire 490 until delivery catheter cap 452 passes through native aortic valve 340 partially into left ventricle 357.

Valve prosthesis 10, typically while still within the catheter, is rotated to align arms 22 with aortic sinuses 364, as described hereinbelow with reference to FIGS. 8A-B or FIGS. 10A-B. Retrograde delivery catheter tube 451 is pulled back (in the direction indicated schematically by an arrow 455), while a device stopper (not shown) prevents valve prosthesis 10 within tube 451 from being pulled back with tube 451, so that engagement arms 22 are released and flare out laterally into the sinuses. At this stage of the implantation procedure, proximal skirt 32 of prosthesis 10 remains in delivery catheter cap 452.

Delivery catheter cap 452 is pushed in the direction of the apex of the heart, using a retrograde delivery catheter cap shaft (not shown) that passes through tube 451 and prosthesis 10. This advancing of cap 452 frees proximal skirt 32 to snap or spring open, and engage the inner surface of the LVOT. Retrograde delivery catheter tube 451 is further pulled back until the rest of valve prosthesis 10 is released from the tube. Retrograde delivery catheter tube 451 is again advanced over the shaft toward the apex of the heart, until tube 451 rejoins cap 452. Retrograde delivery catheter 450 and guidewire 490 are withdrawn from left ventricle 357, and then from ascending aorta 360, leaving prosthesis 10 in place.

For some applications, prosthesis 10 is implanted using techniques described with reference to FIGS. 9A-G in above-mentioned U.S. application Ser. No. 12/050,628.

Reference is made to FIGS. 7C-7E, which are schematic illustrations of an implantation procedure of an alternative configuration of valve prosthesis 10, in accordance with an embodiment of the present invention. In this configuration, valve prosthesis 10 does not comprise proximal engagement arms 22. Even without these arms, which rest in the sinus floors and thus may aid in properly rotationally aligning the prosthesis, the techniques described herein achieve proper alignment of the prosthesis. For some applications, valve prosthesis 10 is configured as described in a U.S. provisional patent application filed on even date herewith, entitled, “Prosthetic heart valve for transfemoral delivery,” which is assigned to the assignee of the present application and is incorporated herein by reference.

FIG. 7C shows valve prosthesis 10 positioned in retrograde delivery catheter 450, which is advanced into left ventricle 357 over guidewire 490. Valve prosthesis 10, typically while still within the catheter, is rotated to align commissural posts 11 with the native commissures, as described hereinbelow with reference to FIGS. 8A-B or FIGS. 10A-B. After the prosthesis is properly rotationally aligned, withdrawal of the catheter causes expansion of the frame of prosthesis, as shown in FIG. 7D. FIG. 7E shows this configuration of prosthesis 10 positioned within the aortic root (viewed from the aorta). The frame of the prosthesis is shaped so as to define distal support members 492, which extend in a downstream direction (i.e., they do not extend into the floors of the aortic sinuses). Distal support elements 492 are configured to rest against the downstream portion of the aortic sinuses upon implantation of valve prosthesis 10, so as to provide support against tilting of the prosthesis with respect to a central longitudinal axis of the prosthesis. As can be seen in FIG. 7E, commissural posts 11 of the valve prosthesis are rotationally aligned with native commissures 494.

Reference is made to FIGS. 8A-B, which are schematic illustrations of valve prosthesis 10 positioned within the aortic root (viewed from the aorta), in accordance with an embodiment of the present invention. As described above with reference to FIGS. 7A-B, during an implantation procedure, a delivery catheter is inserted into an overtube and advanced until the distal end of commissural posts 11 arrive near the end of the overtube. For configurations of valve prosthesis 10 that include proximal engagement arms 22, the arms are still within the catheter. To properly rotationally align posts 11 with the native commissures, the physician rotates valve prosthesis 10 under fluoroscopy until one 496 of commissural posts 11 is aligned with one of the native commissures, such as commissure 226 between the right and left sinuses (C_(RL)). In an attempt to achieve such a rotational position, the physician rotates the prosthesis until one of openings 16 that serve as radiographic identifiers is centered from the viewpoint of the fluoroscopic LAO projection such as shown in FIG. 6B (openings 16 are not visible from the view of FIGS. 8A-B). The other two commissural posts 11 flank the centered post.

At this stage of the procedure, because the radiographic image is two-dimensional and all of the posts appear in the image as though they are in the same plane, it is difficult for the physician to ascertain whether commissural post 496 selected for alignment is:

-   -   (1) in the desired rotational position, closer to fluoroscopy         detector 212 (FIG. 3) than are the other two commissures, and         thus properly aligned with the C_(RL) 226, as shown in FIG. 8A;         or     -   (2) farther away from the fluoroscopy detector than are the         other two posts, rotated 180 degrees from the desired rotational         position, as shown in FIG. 8B. In this rotational orientation,         centered post 496 projects itself onto C_(RL) 226, but actually         faces the noncoronary sinus (N) away from the fluoroscopy         detector, such that valve prosthesis 10 is misaligned by 60         degrees (because the prosthesis typically has three-fold         rotational symmetry).

Reference is made to FIG. 9, which is a flow chart that schematically illustrates a method 500 for ascertaining whether the posts are in the first or second possible rotational position, in accordance with an embodiment of the present invention. At an initial rotation step 502, the physician slightly rotates valve prosthesis 10. At an apparent rotation check step 504, the physician ascertains whether the radiographic identifier on the selected post appears to move in the radiographic image in the same direction as the rotation. If the identifier appears to move in the same direction as the rotation, the physician ascertains that the selected post is correctly rotationally aligned in the desired position (1) (after the physician slightly rotates the prosthesis in the opposite direction to return it to its initial position), at a proper alignment ascertainment step 506. If, on the other hand, the radiographic identifier appears to move in the direction opposite the direction of rotation, the physician ascertains that the selected post is incorrectly rotationally aligned in position (2), at an improper alignment ascertainment step 508. To correct the alignment, the physician rotates the valve prosthesis approximately 60 degrees in either direction, thereby ensuring that one of the two other posts is now rotationally aligned in position (1), at an alignment correction step 510. (The valve prosthesis typically has three-fold rotational symmetry, such that rotation of 60 degrees is sufficient to properly align one of the posts with the selected native commissure, and the prosthesis need not be rotated a full 180 degrees.) For example, assume that at initial rotation step 502 the physician rotates the prosthesis clockwise, as viewed from the aorta. If the valve prosthesis is properly aligned, the radiographic identifier on the selected post appears to move toward the LCS at apparent rotation check step 504. Once the valve prosthesis is properly aligned, commissural posts 11 are released from the catheter, as well as proximal engagement arms 22, for configurations of the prosthesis that include such arms, at a commissural post release step 512. In these embodiments, openings 16 through posts 11 that define the radiographic identifiers may assume any convenient shape, such as a slit.

In an embodiment of the present invention, this technique for rotationally aligning posts 11 with the native commissures is used for aligning a valve prosthesis that does not include radiographic identifiers. Instead of using such identifiers, the physician observes elements of the prosthesis that are discernable in the radiographic images, such as posts 11.

FIGS. 10A and 10B are schematic illustrations of reflection-asymmetric radiographic identifiers 600 on commissural posts 11, in accordance with respective embodiments of the present invention. Identifiers 600 may be used with both the configuration of valve prosthesis 10 described hereinabove with reference to FIG. 1, and that described hereinabove with reference to FIGS. 7C-E. Openings 16 that define radiographic identifiers 600 are shaped to be reflection-asymmetric along respective post axes 604 that are generally parallel central longitudinal axis 13 of prosthesis 10 when the posts assume their collapsed position. For example, as shown in FIG. 10A, identifiers 600 may be shaped as one or more reflection-asymmetric letters of the alphabet, such as B, C, D, E, etc, or numbers. Alternatively, the identifier may be shaped as any reflection-symmetric symbol, such as the inverted elongated L shown in FIG. 10B. The physician can thus readily identify the true orientation of the selected post that appears to be rotationally aligned with the selected native commissure. If the identifier on the selected post appears in the correct left-right orientation, the selected post is aligned in the desired position (1), as described hereinabove with reference to FIGS. 8A-B. If, on the other hand, the identifier appears as the mirror image of its correct left-right orientation, the selected post is incorrectly rotationally aligned in position (2) as described hereinabove with reference to FIGS. 8A-B. To correct the alignment, the physician rotates the valve prosthesis approximately 60 degrees in either direction, thereby ensuring that one of the two other posts is now rotationally aligned in position (1).

For some applications, such as shown in FIG. 10A, at least one of commissural posts 11 is shaped so as to define both reflection-asymmetric radiographic identifier 600 and another reflection-symmetric shape 610, such as a slit. For example, such a slit may have a mechanical purpose, such as coupling valve 104 to support structures 12 and 14, as described hereinabove with reference to FIG. 1. Alternatively, the physician may use reflection-symmetric shape 610 for rotational orientation as described hereinabove with reference to FIGS. 8A-B in the event that reflection-asymmetric radiographic identifiers 600 are not be clearly visible in the radiographic image during a particular implantation procedure.

For some applications, reflection-asymmetric radiographic identifiers 600 are not defined by openings 16, but instead comprise a material having a radiopacity different from (greater or less than) the radiopacity of other portions of the posts. For some applications, a portion of valve prosthesis 10 other than commissural posts 11 comprises radiographic identifiers 600 (whether defined by openings, or comprising a material having a different radiopacity).

For some applications, techniques described herein are performed in combination with techniques described in a U.S. provisional patent application filed on even date herewith, entitled, “Prosthetic heart valve for transfemoral delivery,” which is assigned to the assignee of the present application and is incorporated herein by reference.

The scope of the present invention includes embodiments described in the following applications, which are assigned to the assignee of the present application and are incorporated herein by reference. In an embodiment, techniques and apparatus described in one or more of the following applications are combined with techniques and apparatus described herein:

-   -   U.S. patent application Ser. No. 11/024,908, filed Dec. 30,         2004, entitled, “Fluid flow prosthetic device,” which issued as         U.S. Pat. No. 7,201,772;     -   International Patent Application PCT/IL2005/001399, filed Dec.         29, 2005, entitled, “Fluid flow prosthetic device,” which         published as PCT Publication WO 06/070372;     -   International Patent Application PCT/IL2004/000601, filed Jul.         6, 2004, entitled, “Implantable prosthetic devices particularly         for transarterial delivery in the treatment of aortic stenosis,         and methods of implanting such devices,” which published as PCT         Publication WO 05/002466, and U.S. patent application Ser. No.         10/563,384, filed Apr. 20, 2006, in the national stage thereof,         which published as US Patent Application Publication         2006/0259134;     -   U.S. Provisional Application 60/845,728, filed Sep. 19, 2006,         entitled, “Fixation member for valve”;     -   U.S. Provisional Application 60/852,435, filed Oct. 16, 2006,         entitled, “Transapical delivery system with ventriculo-arterial         overflow bypass”;     -   U.S. application Ser. No. 11/728,253, filed Mar. 23, 2007,         entitled, “Valve prosthesis fixation techniques using         sandwiching”;     -   International Patent Application PCT/IL2007/001237, filed Oct.         16, 2007, entitled, “Transapical delivery system with         ventriculo-arterial overflow bypass,” which published as PCT         Publication WO 2008/047354; and/or     -   U.S. application Ser. No. 12/050,628, filed Mar. 18, 2008,         entitled, “Valve suturing and implantation procedures.”

It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof that are not in the prior art, which would occur to persons skilled in the art upon reading the foregoing description. 

The invention claimed is:
 1. Apparatus comprising a valve prosthesis, which comprises: a prosthetic heart valve; and three or more commissural posts each formed of a material, to which the prosthetic heart valve is coupled, which posts are arranged circumferentially around a central longitudinal axis of the valve prosthesis, and are configured to assume a collapsed position prior to implantation of the prosthesis, and an expanded position upon the implantation of the prosthesis, wherein the three or more commissural posts includes a first commissural post, the first commissural post being provided with a radiographic identifier that is shaped to be reflection-asymmetric about an axis of the first commissural post that is generally parallel with the central longitudinal axis when the three or more commissural posts assume the collapsed position, and further wherein the first commissural post is shaped to define an opening through a thickness of the material of the first commissural post such that the opening does not include the material of the first commissural post, the opening defining an entirety of the radiographic identifier such that the radiographic identifier is bounded by the material of the first commissural post and is void of the material of the first commissural post, the opening having a reflection-asymmetric shape about the axis of the first commissural post, and even further wherein upon final assembly of the apparatus, a radiopacity of the apparatus at the radiographic identifier is less than a radiopacity of the material of the first commissural post.
 2. The apparatus according to claim 1, wherein the radiographic identifier has the shape of one or more reflection-asymmetric characters.
 3. The apparatus according to claim 1, wherein the valve prosthesis comprises exactly three commissural posts.
 4. The apparatus according to claim 1, wherein the opening is at least partially filled with a pliant material of the prosthetic heart valve.
 5. The apparatus according to claim 1, wherein the opening is at least partially filled with a material that is more radiolucent than a material of the commissural posts. 